/*
 * Copyright (c) 2013, marco.tamburelli@gmail.com
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met: 
 * 
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.omorphdb.core.io;

import java.io.IOException;
import java.nio.channels.FileChannel;

/**
 * Base class of page representation.
 */
abstract class AbstractPage
{
	final FileChannel channel;
	long pagePosition;
	final int pageSize;

	protected AbstractPage(FileChannel channel, long pagePosition, int pageSize) throws IOException
	{
		this.channel = channel;
		this.pagePosition = pagePosition;
		this.pageSize = pageSize;
	}

	/**
	 * Return the position of the current page within the file.
	 * 
	 * <br>
	 * The page position is the position of the first byte of the page within
	 * the parent file.
	 * 
	 * @return The position of the current file within the file.
	 */
	long getPagePosition()
	{
		return this.pagePosition;
	}

	/**
	 * Returns the position of the cursor within the file. <br>
	 * The cursor is the place where the next read/write operation will take
	 * effect.
	 * 
	 * @return The current cursor position
	 */
	abstract long getCursorPosition();
}
